FR2691699A1 - Disposable pallet made from corrugated cardboard - Google Patents

Abstract

The pallet is made from corrugated cardboard using a minimum of clips and mainly secured by adhesive. The ground support blocks (2) are made from layers of board and can be waterproofed by impregnating with a preservative. The multilayer load surface (1) is made in one piece with folded side flaps to assembly into the tray.The load layers are in alternate directions for strength. The ground support blocks are glued to the load surface. The adhesive used is suitable for recycling the board.

Description

 The invention relates to a pallet construction system, consisting of a base surface or floor and at least two supports, in particular for corrugated pallets of flat shape and for corrugated pallets forming a container, the supports having a height. which, in view of the stacking of the pallet, allows the passage of the fork of a forklift truck from several sides, in particular from two or four sides, as well as a process for its manufacture.

 Pallets are generally standardized according to DIN 15146, sheet 2. They are usually made of wood or steel, in special cases also of cardboard or paper, and are used for the transport of different kinds. merchandise. As their external dimensions are mutually agreed, the pallets can easily be stacked in the loaded or empty state.

 According to Lueger, Fördertechnik, volume 2, page 315, 1972, it is also possible to assemble pallets in so-called block warehouses for stackable goods. Pallets that have already been loaded can also be stacked in block-type warehouses and be recycled in this state for reuse.

 Due to the increased requirements for environmental protection, there is an increasing desire to pass packaging through closed circuits of raw materials. One of the materials that can be used for such packaging is corrugated cardboard, since it consists of approximately 70% old paper and can be discarded and transformed back into raw paper in a non-hazardous manner. polluting.

 However, in many cases, the required stability and robustness are not obtained, especially on wet soil, so that the use of materials of this type has so far been unimportant.

 The strength requirements for the pallet supports in particular have become more stringent since these supports often serve, during handling with forklifts, as impact edges or as lateral guides during the engagement of the fork teeth in the lower part of the pallet. The pallet supports are also mechanically stressed to a significant extent on the roller conveyors used more and more frequently in the handling sector, since such conveyors do not provide a flat surface for receiving the loads and it arrives in more than the pallets tilt and get stuck in the intervals between the rollers.

 The purpose of the present invention is to create a non-polluting and fully recyclable pallet, which meets the requirements as to the required solidity and use on wet ground. In addition, the pallet must be usable on roller conveyors in the sense that it must resist without significant damage to mechanical stresses during handling on such conveyors.

 This is obtained with a pallet construction system as indicated at the start, which is characterized in that the floor consists of corrugated cardboard with one or more grooves (one or more grooved thicknesses), and shouts the supports are made several strips of corrugated cardboard glued together, the corrugations of the cardboard strips being perpendicular to the floor and their lower ends forming the support face of the support.

 Other features, preferred enhancements, and an easy-to-automate process for manufacturing such a pallet construction system are shown below.

 To reinforce the floor, you can laminate two double-flute cartons whose corrugations are mutually offset or rotated. The use of multi-layer cardboard with corrugated crossings increases the rigidity of the floor by at least 30%. In order to obtain even better characteristics with regard to rigidity, a greater number of corrugated cartons can be superimposed by alternately crossing the corrugations. : 1The bonded assembly is preferably carried out by lamination, with application of the adhesive over a large area.

 It is also possible to use triple groove cardboard for the floor, either with three grooves oriented in parallel, or with a crossed orientation of the middle groove.

 The different layers of the floor are to be arranged depending on the type of load, for example depending on whether it is a point load or acting on a larger or smaller surface or depending on whether it is a centered or off-center load.

 In applications where it is important that the pallet has a high load capacity, the undulations of the floor must always be perpendicular to the longitudinal direction of the supports.

This remark also applies to floors made up of corrugated boxes arranged in a cross, with orientations of the corrugations mutually offset by 900, or made up of fluted systems with several layers. An optimal solution is obtained, with regard to weight and rigidity, with triple-fluted cartons, possibly having different heights of the corrugations.

 In a humid environment, for example when the air is very humid or the pallets are directly exposed to moisture, the supports should be made of strips of impregnated corrugated cardboard.

Impregnation can be carried out by applying a liquid adhesive, preferably by application with a brush, for example on the open sides of the corrugated cardboard. The supports whose corrugated cardboard strips are oriented vertically, so that the groove is in a way arranged upright and the support face of the support is formed by an open side of the groove, can be stiffened by immersing them in a liquid adhesive.

 According to a particularly favorable method of impregnation, the lower side of the sup-ports is immersed, with grooves arranged vertically, in a bath of liquid adhesive, until the adhesive is mounted in the supports, against gravity.

In order to obtain sufficient insensitivity to humidity, it is necessary to impregnate about a third of the height of the supports. The liquid adhesive is sucked up to this height - against gravity by capillarity.

 The adhesive is preferably quick-setting and can in particular be formed from an adhesive to which water is added to adjust the pH to 5.8 - 6.8 and the viscosity to 45 - 49 mPa.s.

 For certain applications, the pallet construction system according to the invention also makes it possible to produce a pallet, the floor of which simultaneously forms a box or a bottom with a raised edge. The floor is made in this case of a grooved cut of corrugated cardboard single flute or double flute, the lateral parts of which are raised to form a box. The angles can be shaped and consolidated by connections with complementary shapes, by the introduction of extensions in the form of legs in cut slots, or mechanically. It is advantageous that the supports are placed laterally inside the outer edge of the floor, so that, when several pallets with box floors are superposed, the supports always come to rest inside the box on the bottom (floor) thereof.

 Pallets are usually made with two or four inlets or passages for the forklift truck. Passage from four sides is also possible with the pallet construction system according to the invention, in which case the supports, consisting of strips of corrugated cardboard glued together, are in the form of so-called dice. placed at the corners of the pallet. In the case of small pallets, provision is made, in order to enlarge the floor, to protrude from the area occupied by the supports, which can be used for the passage of the fork.

 The invention is essentially based on the concept which consists in combining a corrugated cardboard floor with at least two supports in strips of corrugated cardboard, giving the undulations of the floor an orientation perpendicular to the longitudinal direction of the supports and making the open sides corrugations of corrugated cardboard strips as contact or support faces of the supports, the corrugations of the supports being placed upright.

 It is particularly advantageous for the floor (1) to consist of two double-flute cartons (7a - d) which are assembled by gluing or laminating while the orientations of their flutes are mutually offset or rotated (Figure 3).

 It is preferable that the floor (1) is formed from a triple-fluted cardboard (7a, b, c) whose corrugations are parallel, as shown in Figure 4. The floor (1) can however also be made of a triple flute cardboard (7a, b, c) according to FIG. 2, the two external flutes of which are arranged with their corrugations in parallel, while the corrugations of the interposed flute cross at right angles to those of the two external flutes.

 In principle, if the floor has several grooves, it is always necessary to superimpose cartons whose corrugations form a right angle between them and the bottoms of the corrugations of the floor must always have an orientation perpendicular to the longitudinal direction of the supports.

 It is also advantageous for the supports to consist of strips of corrugated cardboard, the groove of which is placed upright and stiffened on its open sides by a liquid adhesive.

 According to a preferred embodiment, the floor is made of a grooved cut out of single or double flute cardboard, the lateral parts of which are folded back to form a box floor (PC), the corners of the box being shaped and mechanically consolidated, by stapling for example or by links with complementary shapes.

 According to the method according to the invention, we first assemble by gluing strips of corrugated cardboard, with their corrugations in parallel, then glue the supports thus formed to the floor of the pallet, so that the grooves of the supports are oriented vertically, that is to say perpendicular to the floor.

 Through the opposite open side of the cardboard strips, the supports are then immersed in a bath of liquid adhesive with a viscosity of 45 - 49 mPa.s.

The adhesive then rises, against gravity, in the slots and tubes of the corrugated cardboard supports, so that a support is obtained which resists water and is rigid in bending after the drying of the adhesive.

 According to the invention, an adhesive is used which is mixed with an adequate quantity of cold water, depending on the field of application, the suitable dissolution of which is obtained after a swelling time of a few hours (at least one hour) and which is then applied at temperatures of the order of 60 C. The pH of this adhesive is 5.8 - 6.8.

Other characteristics and advantages of the invention will emerge more clearly from the description which follows of several nonlimiting exemplary embodiments, as well as from the appended drawings, in which:
- Figure 1 is a perspective view of three pallets stacked on top of each other, with passages of the fork of a forklift from two sides for the two top pallets, along the arrow, and with passages for the fork from the four sides, also along the arrow, for the bottom pallet, FIG. 1A showing on a larger scale the detail A and FIG. 1B showing on a larger scale the detail B of FIG. 1;
- Figure 2 is a partial perspective view of a stack of pallets, corresponding to the right front corner of the representation of Figure 1, but relating to pallets whose floor (1) consists of a carton triple groove, the middle groove of which is crossed with respect to the others, FIGS. 2A and 2B being again enlarged representations of a support and of detail B;
- Figure 3 is a view similar to Figure 2, but showing pallets with floors each consisting of two boxes whose double grooves are arranged in a cross, Figures 3A and 3B again showing on a larger scale a support and the detail B;
- Figure 4 is also a view similar to Figure 2, but with pallet floors each consisting of a triple corrugated cardboard with parallel corrugations, Figures 4A and 4B being again enlarged representations of a support and detail B;
- Figure 5 is a top view of a grooved cutout, flat, for the formation of a pallet construction system with floor-box according to the invention, Figure 5A being a partial perspective view and larger scale of a support for such a system and FIG. 5B being a perspective view of a pallet comprising the floor-box formed from the cutout in FIG. 5 and two supports like that partially represented in FIG. 5A; and
- Figure 6 is a top view of a grooved cutout, flat, for the production of a checkout floor, Figure 6A is a perspective view on a larger scale of a corresponding support and Figure 6B is a perspective view of the assembled pallet when the lower parts of the supports are immersed in a bath of liquid adhesive.

 The stack of pallets according to FIG. 1 is made up of three superimposed pallets each having a floor I and corresponding supports. The dimensions of the pallets correspond to DIN 15146, sheet 2, for passage and handling by means of forklifts. The bottom palette has dice 2a, b and 3, 4 at the angles for the entry and passage of the fork from four sides.

 The details of Figures 1A and 1B show how to be oriented, in accordance with the invention, ôfldulations in the supports and in the floors. In the supports 2a, b as well as 3 and 4, the corrugations are arranged upright, that is to say oriented vertically, so that, on one side, the open ends of the sinusoidal corrugations form a bearing face 5 (detail A) of the support.

 The corrugations of the single groove of the floor 1 of this example (detail B) have an orientation perpendicular to the corrugations in detail A. The floors 1 are therefore more rigid, in the direction in which they are loaded, than a carton compact since they have a sandwich construction obtained by assembling by gluing a top layer 1a, a bottom layer 1b and the groove lc placed between them.

In the representation according to FIG. 2, the support 2a is visible from below, in perspective, on a larger scale. We perceive the undulations, oriented vertically, which are stuck in the contact area
X at floor 1 and reinforced on the opposite open side
Y, forming the support face 5 of the support, by an adhesive.

The corrugations 6 of this support are therefore oriented at right angles to the corrugations 6 of the floor 1.

 According to the invention, the adhesive used in contact area X is a quick-setting adhesive for the manufacture of corrugated boxes or boxes and helical rolled tubes, as well as for laminating paper / paper and paper / microcannellated cardboard. . This adhesive consists of a dispersion of polyvinyl acetate having the following technical characteristics: color: t white solid content: 52 - 54% density: 1.05 g / cm3 viscosity (Brookfield, 20 rpm, 230 C ): 3,000 - 5,000 mPa.s pH: 6 - 7.

 In a preferred embodiment, according to FIG. 2B, the floor 1 consists of a triple-fluted cardboard whose corrugations 7a, 7b, 7c are each rotated by 90 "relative to the neighboring layer. This arrangement provides an increase additional rigidity of the floor 1. The production is possible in a single operation by a cardboard production machine. It is possible to increase the number of corrugated cartons assembled by gluing in such a system, with cross corrugations, by providing only a lamination, as described previously (page 3).

 In the case illustrated in Figure I, the floor 1 is a single groove, but it is also possible to use several layers, depending on the stiffness needs. To increase the rigidity of the floor 1, corrugated cardboard is assembled by gluing, as shown in FIG. 2, the corrugations of which cross and are in particular offset or mutually turned by 900 to form the floor.

 According to Figures 3 and 3B, to form the floor 1, a double-fluted cardboard 7a, 7b is assembled by gluing to another double-fluted cardboard 7c, 7d so that the corrugations of the flutes 7a, 7b cross those of the flutes 7c, 7d .

 Figures 4 and 4B show a floor 1 whose structure is triple grooved, in which the corrugations 6 of the three grooves 7a, 7b and 7c are oriented parallel, as can be clearly seen in detail B.

 Figures 5, 5A and 5B show a pallet construction system consisting of a floor 1 made of a single or double flute cardboard which has been deformed to form a PC body floor and glued to supports 9, 10 , the cardboard in the unfolded state forming a roughly rectangular cutout in which creasing lines delimit a roughly rectangular bottom 1/8 and lateral parts which should constitute a raised edge. The lateral parts 16 - 19 are folded along the crease lines 11, 13, 14 and 15 and the tabs 20, 21, 23, 24 are introduced into the slots 25 - 28 cut in the bottom. The raised edge can thus be held in place, so that the material to be transported received in the box is protected against slipping and falling or lateral stresses.

 The insertion of the legs in the cut slots corresponds to the creation of connections by complementarity of shapes. Other connections of this type are also possible, such as for example by folding down or by forming an outwardly folded rim.

 When transporting empty pallets, it is often advantageous to lay the side parts flat if the transport volume is to be reduced. A maximum reduction of this volume is obtained by removing the tabs from the side parts and folding the entire cut out on the bottom 1/8.

 Stacking / nesting: mutual pallets with such raised edges becomes easier when the supports 9, 10 are offset inwards relative to the edge of the floor, so that the supports are placed, during stacking, in the opening - located at the bottom or at the top - of the neighboring checkout floor.

 FIG. 6B shows how a pallet is immersed by the lower parts of the feet 30, 31, 32 (the fourth foot is invisible) in a bath of adhesive 29. During this operation, the adhesive rises in the feet or supports, against gravity, under the effect of capillarity. It is generally sufficient for about a third of the supports to be wetted by the adhesive.

 The supports are then sufficiently impregnated to also maintain sufficient rigidity in a humid environment. Thus, the pallet shown in FIG. 6B has a sufficient support capacity, depending on the surface of the ground or of another surface which supports it, which can go up to 150 kg. It can be laid without time limit on a floor covered with humidity.

 In the case of the pallet construction system illustrated in FIGS. 6, 6A and 6B, the connections to the corners are made mechanically. It is possible, for example, to place several staples 37 -40 in the folded corners 33 - 36 of the cutout shown in FIG. 6 and from which the box floor PC of FIG. 6B is formed. Other types of fixing are however also possible, such as riveting or assembly by folding-insertion. Reference 41 designates the upper edge of the body. As bath adhesive 29, an adhesive having the composition described on page 4 is preferably used.

Claims (13)

I. Pallet construction system, in particular corrugated cardboard for flat pallets and pallets forming a container consisting of at least one base surface or floor and at least two supports which, for stacking purposes of the pallet, have an appropriate height for the passage of the fork of a lift truck from two or four sides, characterized in that the floor (1) consists of corrugated cardboard with one or more grooves (one or more grooved thicknesses), and that. supports (2, 3, 4) consist of several strips of corrugated cardboard glued together, the corrugations (6) of the cardboard strips being perpendicular to the floor (1) and their lower ends forming the support face (5) of the support . 2. Pallet construction system according to claim 1, characterized in that the floor (1) consists of two double flute cartons (7a - d) which are assembled by gluing or laminating. 3. Pallet construction system according to claim 1, characterized in that the floor (1) consists of a triple flute cardboard (7a, b, c) whose corrugations are oriented parallel. 4. Pallet construction system according to claim 1, characterized in that the floor (1) consists of a triple flute cardboard (7a, b, c) whose two outer flutes have parallel undulations and the intermediate flute is oriented so that its corrugations cross the corrugations of the two outer grooves at right angles. 5. Pallet construction system according to any one of the preceding claims, characterized in that, in the case where the floor (1) comprises several grooves, the superposed cartons are always oriented so that the undulations of two cartons which follow one another are mutually offset at right angles. 6. Pallet construction system according to any one of the preceding claims, characterized in that the undulations of the floor (1) are perpendicular to the longitudinal direction of the supports. 7. Pallet construction system according to any one of the preceding claims, characterized in that the supports consist of strips of corrugated cardboard whose groove is oriented vertically and reinforced by a liquid adhesive with open ends. 8. Pallet construction system according to any one of the preceding claims, characterized in that the floor (1) is made of a grooved cut out of single or double fluted cardboard, having a bottom and foldable side parts to form a floor-box (pu). 9. Pallet construction system according to claim 8, characterized in that the angles of the floor-box (PC) are. shaped and mechanically consolidated by stapling. 10. Pallet construction system according to claim 8, characterized in that the angles of the floor-box (PC) are shaped and consolidated by links with complementary shapes. 11. Pallet construction system according to any one of the preceding claims, characterized in that the supports or dice (2, 3, 4, 9, 10, 12, 30, 31, 32), forming the feet of the pallet , are connected to the floor (1) or to the bottom (1/8) of the body floor (PC), in line with contact zones (X), by an adhesive in the form of a dispersion of polyvinyl acetate having the following technical characteristics: color: white solid content: 52 - 54% 3 density: 1.05 g / cm viscosity (Brookfield, 20 rpm, 230 C): 3,000 - 5,000 mPa.s pH: 6 - 7. 12. Method for manufacturing a pallet construction system according to any one of the preceding claims, characterized in that iton assembles by gluing the floor (1) with the upper sides of the supports (2, 3, 4), consisting of several strips of corrugated cardboard glued together, then the lower side of the supports is immersed, forming the support face (5) and in which the vertically oriented corrugations end, in a bath (29) of liquid adhesive, until the adhesive is mounted in the supports against gravity. 13. Method for the manufacture of a pallet construction system according to any one of claims 8 to 10, characterized in that the floor (1, 1/8) is produced from a piece of simple fluted cardboard or double groove with lateral extensions to form a raised edge (16 - 19), with provision for extensions in the form of legs (20, 21, 23, 24) on two opposite sides of the edge, legs which are introduced after the raising of the edge, in slots (25, 26, 27, 28) cut at appropriate places in the central part forming the floor (1/8) of the piece of cardboard.